TAIPEI, Taiwan (AP) — The disciplinary panel of Taiwan’s ruling party suspended the speaker of the legislature Wednesday, a move that could fracture the party and threaten its efforts to develop closer ties with China.

Wang Jin-pyng was suspended for allegedly pressuring prosecutors not to appeal the acquittal of an opposition lawmaker. That removes him from the party for a year, after which he can apply for reinstatement.

Wang contends he did nothing improper. He has held the legislative speakership, one of Taiwan’s most powerful positions, since 1999, and is known for having relatively good relations with the opposition. Though he and President Ma Ying-jeou both belong to the Nationalist Party, the two have been bitter rivals.

The fast-moving political drama could threaten the unity of the party, which under Ma has lowered tensions between Taiwan and China to their lowest level since the two sides split amid civil war 64 years ago.

Ma pressed hard for Wang’s ouster, calling his alleged action “the most serious infringement in the history of Taiwan’s judiciary.” But in doing so, he has drawn criticism not only from the opposition, but also from many Nationalists who see his pursuit of Wang as a personal vendetta.

A Nationalist split would improve the prospects of the China-wary opposition in the 2016 elections. Ma is currently among the most unpopular presidents in Taiwan history, with an approval rating of just 15 percent.

The drama began Friday, when the Special Investigation Division of the Prosecutor’s Office announced it had evidence that Wang and former Justice Minister Tseng Yung-fu had colluded to pressure prosecutors not to appeal the acquittal of opposition lawmaker Ker Chien-ming, a friend of Wang’s, on breach of trust charges. Tseng resigned later that same day under heavy pressure from Ma, but insists he did nothing wrong.

The SID’s evidence was gathered from a wiretap on Ker’s cell phone, leading to opposition charges — echoed by some Nationalists — that the agency abused its power. The SID says its wiretap was legal.

Ma then unleashed a barrage of criticism at Wang. The two have a long history of animosity, dating back at least to 2008, when they competed for the Nationalist presidential nomination. Wang recently upbraided Ma for his handling of government and the economy.

Wang’s suspension by the Nationalist committee on Wednesday effectively strips him of the legislative speakership and even his legislative seat, because he was selected in the last legislative election not by popular vote, but as an at-large Nationalist candidate.

At 72, the diminutive Wang still maintains a number of credible political options, including establishing a breakoff party of his own, though Wang said Tuesday he was not interested in such a move.

With Wang removed from the legislative speakership, Taiwan’s often fractious legislature can be expected to become more fractious still, largely because of his strong channels of communication with the opposition.

It was not clear who the next speaker will be. One of that lawmaker’s first big tests will be to try to win legislative approval of a bilateral services agreement in China. The opposition says the legislation would give China too much control of the Taiwanese economy.

Despite Wang’s own Nationalist pedigree, and the heavy Nationalist majority in the legislature, Wang did little as speaker to press for the approval the pact needs to enter into force.